Robert Lewandowski put Bayern ahead against the Russian runner-up from the penalty spot and Thomas Muller slammed in a David Alaba cross before halftime to make it 2-0. Joshua Kimmich turned in a Douglas Costa cross to make it three and headed a fourth soon after before Juan Bernat made it 5-0. In the same group Atletico Madrid won a controversial game 1-0 away to PSV Eindhoven on a volley from Saul Niguez.

Arsenal overcame a poor first half away to Paris Saint-Germain to snatch a valuable point in a 1-1 draw, with Alexis Sanchez canceling out Edinson Cavani’s opener in a game that ended in red cards for Olivier Giroud and Marco Verratti. It was a similar story in the other game in the group as Ludogorets was denied its second-ever Champions League victory after a late equalizer from Basel’s Renato Steffen. The Bulgarian champion’s only previous victory had come in Basel, and it looked on course to repeat that when Jonathan Cafu put it ahead after a classic breakaway in the first half. But a goalkeeping error allowed Steffen to angle in a volley with 10 minutes remaining.

Elsewhere, Arkadiusz Milik scored with two headers as Napoli came from behind to win 2-1 away to Dynamo Kiev. Dynamo had taken an early lead through Denys Garmash and had Serhiy Sydorchuk sent off midway through the second half after collecting a second yellow card for a dive.

In the other game in the group, an injury-time free kick from Anderson Talisca, on loan from Benfica, earned Besiktas a point against his parent club. Young Argentinian summer signing Franco Cervi had followed in to put Benfica ahead after Tolga Zengin had blocked Eduardo Salvi’s shot.

Here are three major takeaways from the opening day of 2016-17 Champions League action:

M-S-N reboots

Messi, Luis Suarez and Neymar started together for Barcelona for the first time this season, and the result was an emphatic victory over Celtic. Neymar played Messi through to hammer in the opener within three minutes, and it was a slick interchange between the two that brought a second for the Argentine. Neymar bent in a free kick early in the second half, Andres Iniesta came off the bench to volley a fourth before Messi completed his hat trick after a one-two with Suarez.

Suarez got the sixth, chesting down a Neymar chip–the Brazilian’s fourth assist of the night–before lashing the ball home. Suarez then flicked in a Messi cross to make it 7-0, Celtic’s heaviest defeat in European football.

Despite being outplayed for long periods, Celtic was given the perfect opportunity to level when Moussa Dembele was tripped in the box by Marc-Andre ter Stegen. The French forward, who scored a hat trick against Rangers on Saturday, saw his spot-kick saved, though, and Celtic never had another chance to gain a foothold.

The real story, though, was the gulf between the sides and the seemingly intractable economic divide at the heart of European football.

Sanchez saves Arsenal

Arsenal did get a point in the end, but for a long time it looked like being another frustrating night in what has been an uneasy start to the season for Arsene Wenger’s side. Looking lackadaisical, as it so often does these days, Arsenal went behind within a minute. Serge Aurier swept down the right and crossed for Edinson Cavani who had gotten in behind new signing Shkodran Mustafi to head past David Ospina.

But the Uruguayan, whose form this season has been poor, proceeded to miss a string of opportunities that would have killed off the game. Arsenal improved in the second half, encouraged by PSG’s wastefulness, and leveled with 12 minutes to go, as Sanchez thrashed in a shot from the edge of the box after Alex Iwobi’s attempt had been saved. Giroud, who was booed by the Parisian crowd as he came off the bench in the second half, looked ill at ease and both he and Verratti had already been booked when they clashed in injury time and collected second yellows.

PSV left furious

English referee Martin Atkinson and his assistants played key roles on a controversial night in Eindhoven. First they disallowed a PSV goal for a slight push–although there may also have been a marginal offside. Then they allowed a spectacular Saul Niguez strike–a jab volley from the edge of the box–to stand despite PSV’s Davy Propper having been involved in a clash of heads that left his face covered with blood.

With the home fans furious, Atkinson gave PSV a highly debatable penalty as Luciano Narsingh tumbled in the vicinity of Jose Maria Gimenez, the Atletico player who had inadvertently inflicted Propper’s wound. Andres Guardado’s penalty, though, was brilliantly saved by Jan Oblak. PSV was denied another penalty when Diego Godin seemed to handle in the second half and walked away with a 1-0 defeat.

Goal of the Day: Jonathan Cafu, Ludogorets vs. Basel

Andres Iniesta scored a stunning volley and Thomas Muller’s finish was superb, but it seems more fitting to look to a goal that mattered. Cafu’s was a neat finish as he latched onto Marcelinho’s pass following an incisive breakaway from a Basel corner.